Many prior art galvanometers are of the suspension type and rely on tortional stress to provide movement for angularly displacing a light-deflecting mirror. Such a galvanometer is chiefly used in measuring devices and is not adaptable to the high accuracy and speed requirements desired for use in conjunction with computers.
Laboratory galvanometers are also known in the prior art. However, this type of galvanometer also does not readily lend itself to the high speed systems required today for information storage and retrieval.
The most commonly used galvanometers have an operating life of about 100 hours at 700 to 1500 Hz. The operating precision and efficiency of such a galvanometer decreases as it is operated throughout this life span to the point where adjustments are continuously necessary in order to maintain an established accuracy within certain limits. This is one of the reasons why the use of a mirror- or a prism-wheel has been advocated because such a multiple-element arrangement avoids the problems encountered by galvanometers of presently known structure. Accordingly, there is a dire need for a galvanometer structure that will continuously and accurately operate over long periods of time without adjustment or degradation of image quality.